On Fri, 15 May 2020 at 22:23, Joseph Myers wrote:
>
> Most x87 instruction implementations fail to raise the expected IEEE
> floating-point exceptions because they do nothing to convert the
> exception state from the softfloat machinery into the exception flags
> in the x87 status word. There is
On Tue, 19 May 2020, Richard Henderson wrote:
> > Note that another bug in the x87 emulation is the lack of setting C1 for
> > most instructions with inexact results based on the direction of rounding
> > (which will require a new feature to be added to the softfloat code to
> > record that inf
On 5/19/20 11:12 AM, Joseph Myers wrote:
> On Tue, 19 May 2020, Richard Henderson wrote:
>
>> To retain the hard float fast path, we need to leave float_flag_invalid set
>> when the accrued exception bit is set. To me this suggests keep all of the
>> FPUS_* bits in fp_status and only convert to F
On Tue, 19 May 2020, Richard Henderson wrote:
> To retain the hard float fast path, we need to leave float_flag_invalid set
> when the accrued exception bit is set. To me this suggests keep all of the
> FPUS_* bits in fp_status and only convert to FPUS_* when we read the fp status
> word.
There
On 5/15/20 2:21 PM, Joseph Myers wrote:
> +uint8_t new_flags = get_float_exception_flags(&env->fp_status);
> +float_raise(old_flags, &env->fp_status);
> +fpu_set_exception(env,
> + ((new_flags & float_flag_invalid ? FPUS_IE : 0) |
> + (new_flag
Most x87 instruction implementations fail to raise the expected IEEE
floating-point exceptions because they do nothing to convert the
exception state from the softfloat machinery into the exception flags
in the x87 status word. There is special-case handling of division to
raise the divide-by-zero
